This invention relates to an ion laser generator.
An ion laser tube comprises a bore, through which plasma is conducted, a cathode for plasma discharge facing to an end of the bore, an anode for plasma discharge facing to the other end of the bore, a pair of Brewster windows for transmitting laser light. And an ion laser generator comprises an ion laser tube, an electromagnet surrounding the ion laser tube, and a pair of light resonating mirrors situated at both ends of the ion laser tube. An electric voltage is impressed between the cathode and the anode for generating the plasma, and an exciting current flows in the electromagnet to generate a magnetic field for converging the plasma around the axis of the bore. When the ion laser tube discharges, the laser light is resonated by the pair of resonating mirrors, and a part of laser light is taken out through one of the light resonating mirrors.
For a numerical example, a magnetic field of about 1000 gauss is required at the bore for a sufficient convergence of the plasma, whereas the magnetic field at the end surface of the cathode must be less than 100 gauss. When the magnetic field at the end surface of the cathode is stronger than 100 gauss, the plasma is concentrated on an area of the cathode and destroys the cathode at the area. On the other hand, when the magnetic field at the bore is not strong enough, insufficient convergence of plasma makes plasma sputtering strong, and sputtered material will stain the Brewster windows.
In a heretofore known ion laser generator, the electromagnet for converging the plasma must be positioned with a sufficient distance apart from the end surface of the cathode in order to obtain a sufficiently decreased magnetic field intensity at the end surface of the cathode while keeping a sufficiently strong magnetic field at the end surface of the bore.
An increase in the distance between the end surface of the cathode and that of the bore decreases the length of the bore in a limited length of an ion laser tube. Since the laser light is generated only in the bore, decrease of the bore length decreases the intensity of the laser output in a limited length of an ion laser tube. This means that the length of an ion laser tube is not effectively used in a heretofore known ion laser generator.